Trampoline structure



FIG. 1 is a perspective view.

FIG. 2 is a front view.

FIG. 3 is a rear view.

FIG. 4 is a left side view.

FIG. 5 is a right side view.

FIG. 6 is a top view; and,

FIG. 7 is a bottom view.

The broken lines illustrate portions of the trampoline which form no part of the claimed design. 

The ornamental design for a trampoline structure, as shown and described. 